1. Field of the Invention
The present invention relates to systems and methods for providing postoperative pain relief and, more particularly, to such systems and methods for local, site-specific, time-released administration of an anaesthetic.
2. Description of Related Art
Anaesthetic medication is generally required postoperatively for alleviation of discomfort at the surgical site. It has been considered desirable to deliver such medication via a single puncture in order to avoid multiple injections adjacent an area that is already painful.
Two such systems are known to have been disclosed: Reese (U.S. Pat. No. Re. 35,192) teaches a cannula and catheter system that is fed by a spring-loaded syringe wherein the spring has nonlinear characteristics that effect a gradually decreasing delivery rate with spring expansion. LeFevre (U.S. Pat. No. 4,997,420) describes a portable drug delivery device for administering a medication at a constant and self-regulated rate. This device includes a spring-loaded syringe having a reverse-taper cylinder to compensate for the decreasing force exerted by the spring as it expands.
Medication-delivery pumps have been marketed for use in oncological applications to deliver chemotherapeutic agents and for the delivery of antibiotics (the xe2x80x9cOutBoundxe2x80x9d pump, McKinley, Inc., Wheat Ridge, Colo., and others). This pump has a flow-control restrictor and a filter to remove particulates.
In some procedures such as orthopedic operations, a patient can feel very comfortable even immediately after surgery because an anaesthetic will have been delivered into the surgical site, such as a joint. Therefore, until that dose of anaesthetic wears off, the patient experiences less post-operative discomfort. When it does wear off, however, the patient is often dependent upon medication to relieve postoperative pain. Such medication may have side effects and may not alleviate the pain completely, as it is circulated systemically and takes time to reach the target site.
It is therefore an object of the present invention to provide a portable system for administering a constant infusion of local anaesthetic directly into a desired site.
It is an additional object to provide such a system for postoperative use.
It is a further object to provide a system for delivering a predetermined amount of medication over a predetermined period of time.
It is another object to provide such a system that is portable and permits patient mobility.
A further object is to provide a method for delivering a constant infusion of local anaesthetic into a wound site.
An additional object is to provide a method for alleviating postoperative discomfort.
Another object is to provide a kit for delivering an anaesthetic-containing fluid to a surgical site.
These objects and others are attained by the present invention, a system for delivering an anaesthetic-containing fluid to a desired site in a patient. The system comprises means for channeling an anaesthetic-containing fluid into a unitary portal penetrating a body. The system also includes pump means that has means for creating a constant flow rate. The pump means is dimensioned to retain sufficient fluid for at least a one-day delivery and is adapted to permit being affixed to the body to permit portability. Additionally, a fluid line, such as tubing, transports fluid from the pump means to the channeling means.
A kit further includes an introducer needle dimensioned to permit the channeling means, such as a catheter, to pass therethrough.
A method of relieving pain at a surgical site postoperatively over an extended period of time includes the steps of inserting an anaesthetic-containing fluid into a pump interior having a capacity sufficient for at least a one-day delivery. The skin of a patient is punctured with an introducer needle at a desired site adjacent the surgical site, and an epidural-type catheter is passed through the introducer needle, which is then removed, leaving the catheter at the desired site.
The catheter is connected to tubing, which is also connected in fluid-receiving relation to the pump interior. Then fluid is permitted to flow from the pump to the desired site.
The features that characterize the invention, both as to organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description used in conjunction with the accompanying drawing. It is to be expressly understood that the drawing is for the purpose of illustration and description and is not intended as a definition of the limits of the invention. These and other objects attained, and advantages offered, by the present invention will become more fully apparent as the description that now follows is read in conjunction with the accompanying drawing.